[Radio Wrangler]

The military bought lots of the 2024 sig gens and then released them onto the surplus market. Many of these have an option set including:

Ovened reference oscillator
Fast pulse modulator
+25dBm output amplifier
2.4GHz coverage.

You can spot them from the front panel because the bottom left BNC is the input for the fast pulse modulator, and the AM/FM mod input BNC is at top right.

The base model 2024 has the AM/FM mod input BNC at bottom left.

So if you see 'pulse' written above the bottom left BNC on a 2024 in the UK, you probably have an ex-military unit with the option pack they had in their contract.

As Jeremy says, these are good, very versatile sig gens. We have a lot of them at work. Calibration fails are mostly OCXOs ageing a little out of tolerance. They aren't the best for adjacent-channel measurements, though, and I break out the HP8662s.

High broadband noise floors are a failing of most modern signal generators, especially those with complex modulation capabilities (I&Q) because of the level the modulators had to run for linearity and the sheer amount of gain needed after them. This limits dynamic range measurements on broadband receivers via the noise versus noise reciprocal mixing process which is quite nasty and not common knowledge.

250v reservoir capacitors are too low a rating for use in a PSU with a 240v input range. I suspect they are used in series pairs to get 500v rating and also the rectifier might be switched to bridge for 240v and voltage doubler for 120v ranges. This is common for higher power supplie as it makes better use of the energy storage capacity of the reservoirs. Low power supplies just bridge rectify the mains and the switcher takes care of mains voltage differences, there is no range switch.

I suspect the open circuit 100k resistors were the bleeders/balancing resistors for the capacitor bank, and that one of them doubled up as the start-up supply.

David